public N0183Defn GetN0183Defn(N0183Frame msg)
{
string headerText = msg.Header.HeaderText;
int defnIndex;
if (_largeTypeCodes.TryGetValue(headerText.Substring(1), out defnIndex))
{
msg.Header = new N0183Header(headerText.Substring(0, 1), "", headerText.Substring(1));
return(N0183Defns[defnIndex]);
}
else
{
if (N0183Dictionary.TryGetValue(msg.Header.TypeCode, out defnIndex))
{
return(N0183Defns[defnIndex]);
}
else
{
return(new UnknownN0183Defn());
}
}
}
public override byte[] GetBytes(Frame frame)
{
N0183Frame n0183Frame = frame as N0183Frame;
if (n0183Frame != null)
{
return(Encoding.ASCII.GetBytes(n0183Frame.FullMessage + "\r\n"));
}
N2kFrame n2kFrame = frame as N2kFrame;
if (n2kFrame != null)
{
return(Encoding.ASCII.GetBytes(FrameConversion.PackN2k(n2kFrame).FullMessage + "\r\n"));
}
AISFrame aisFrame = frame as AISFrame;
if (aisFrame != null)
{
// TODO : Breaking up message if too long
int padbits = 6 * aisFrame.AISData.AISString.Length - 8 * aisFrame.AISData.AISBytes.Length; // [0, 5]
string message = "!AIVDM,1,1,,A," + aisFrame.AISData.AISString + "," + padbits;
// Add checksum
byte checksum = 0;
for (int i = 1; i < message.Length; i++)
{
checksum ^= Convert.ToByte(message[i]);
}
message += "*" + checksum.ToString("X2");
return(Encoding.ASCII.GetBytes(message + "\r\n"));
}
throw new Exception("Attempt to send unknown frame type: '" + frame.GetType().Name + "'");
}
// Public functions
public override int ProcessBytes(byte[] bytes, int offset, int size)
{
int numRead = 0;
for (int i = 0; i < size; i++)
{
byte nextByte = bytes[offset + i];
bool startCharRead = (nextByte == startChar1) || (nextByte == startChar2);
bool endCharRead = (nextByte == endChar1) || (nextByte == endChar2);
if (waitingForStart)
{
if (endCharRead)
{
// We skip over end characters while waiting for start (There is no requirement to read them all when finishing a frame)
}
else if (startCharRead)
{
// Read in start character, toggle flag
_bufferIdx = 0;
_buffer[_bufferIdx++] = nextByte;
waitingForStart = false;
}
else
{
// Start byte does not match, return
return(numRead);
}
}
else
{
if (startCharRead || endCharRead)
{
if (startCharRead)
{
i--;
}
// End character read, and we don't add it to the buffer (Would be trimmed by frame constructor anyway)
// Grab message from buffer
string msgData = Encoding.ASCII.GetString(_buffer, 0, _bufferIdx);
// Create message
Frame createdFrame = N0183Frame.TryCreate(msgData, DateTime.Now);
if (createdFrame != null)
{
OnFrameCreated(createdFrame);
}
// Reset flags and return
waitingForStart = true;
numRead = i + 1;
}
else
{
_buffer[_bufferIdx++] = nextByte;
}
}
}
// Read entire byte[] given.
return(size);
}
